determinant vs decisive

determinant is a noun but decisive is not a noun.

Word	Noun	Adjective	Verb	Adverb
determinant	Yes	Yes	No	No
decisive	No	Yes	No	No

determinant (noun)	decisive (noun)
a determining or causal element or factor
a square matrix used to solve simultaneous equations
the site on the surface of an antigen molecule to which an antibody attaches itself

determinant (adjective)	decisive (adjective)
having the power or quality of deciding	determining or having the power to determine an outcome
	characterized by decision and firmness
	forming or having the nature of a turning point or crisis
	unmistakable